The film mainly tells the story of a stewardess who could not bear the long-term domestic violence. She brutally killed her husband in a thunderstorm late at night and wanted to die. Finally, she regained her confidence in life with the help of a legal aid lawyer. In a dimly lit and messy room, Ouyang Zhihe, with ragged clothes, bloody mouth corners, messy hair and desperate eyes, walked barefoot to the sofa in the living room with a golf club. Zhihe's expression changed from cold to angry. He raised the golf club and smashed it violently at Zhang Ziying with thunder and lightning. The glass bottle filled with paper cranes on the table was broken, glass splashed, paper cranes scattered all over the floor, and the photo of Zhihe in a stewardess uniform and a photo of a family of three on the wall were splashed with blood. The white paper cranes scattered on the ground were stained red with blood. Zhang Tong, Ouyang Zhihe's legal aid lawyer, went to the detention center to understand the situation. Seeing that Zhihe had given up the idea of living, Zhang Tong felt that there must be something else behind the case. Zhang Tong was anxious and quickly launched an investigation and evidence collection. Zhang Tong came to the detention center many times to talk with Ouyang Zhihe and tell him about her experience. Zhang Tong encouraged Zhihe to be strong for her son Duoduo and not give up. After many efforts, Zhihe told the truth about Zhang Ziying's drug abuse and domestic violence against her for two years. Zhang Tong found the video of Zhang Ziying's inhumane domestic violence against Ouyang Zhihe from the video of the intelligent robot, as well as the video evidence of Zhang Ziying's drug use. On the day of the trial, Zhang Tong encountered a traffic accident. With the assistance of Mao Yi, Zhang Tong successfully appeared in court. The judge finally found Ouyang Zhihe guilty of murder, but because Zhang Ziying had drug abuse and domestic violence, he reduced the sentence according to law and sentenced Ouyang Zhihe to 15 years in prison. Three months later, Zhihe, dressed in prison uniform, was doing exercises on the prison playground. Outside the high wall, Zhang Tong ran with Duoduo and controlled the drone remotely. The drone dragged a string of paper cranes with a banner that read "Come on, Mom! I love you!" hovering in the air.